The "inactivated vaccine (using a virus that has eliminated infectivity)", which is currently widely used for influenza prevention, is highly effective against the viral strains used in the vaccine, but has newly emerged (new type). There is a problem that it is not effective against virus strains.On the other hand, "live attenuated vaccine (using attenuated virus)" has been shown to be effective against new viruses.
It is thought that the reason why live attenuated vaccines can protect against infection beyond viral strains is that "widespread neutralizing antibodies" that can counter viruses with different structures are produced, but the mechanism is detailed. Not clear.Therefore, a joint research group of RIKEN and Tokyo University of Science investigated the qualitative and quantitative differences between the antibodies produced by the inactivated vaccine and the live attenuated vaccine.The results showed that inactivated vaccination produced only antibodies that could counteract the virus strain used in the vaccine, whereas nasal virus infections that mimic live attenuated vaccines produced broad-spectrum neutralizing antibodies. ..
Subsequent experiments revealed the mechanism by which live viral infections produce broad-spectrum neutralizing antibodies:First, viral infection activates follicular helper T cells and induces interleukin-4 (IL-4) production. The action of IL-4 promotes the proliferation of B cells, which are antibody-producing cells.From among the proliferated B cells, selection of B cells that recognize epitopes (antigen determinants) common to viral strains is being promoted, which will lead to the production of broad-spectrum neutralizing antibodies.
This result clarified the effectiveness of a live vaccine that can efficiently produce broad-spectrum neutralizing antibodies, and will lead to the development of a "universal vaccine" to counter the new influenza virus and new corona virus that are feared to emerge in the future. Expected to contribute.
Paper information:[Nature Communications] Influenza virus infection expands the breadth of antibody responses through IL-4 signalling in B cells
